The following prior art is described as techniques in relation to energy transfer in a vehicle. In a power generation system including an energy storage for storing electrical energy, a system efficiency determination device operates as follows: it constantly determines energy efficiency related to the energy storage; when electrical energy is being accumulated in the energy storage, it determines the energy efficiency of the entire system from fuel energy, which is obtained by subtracting energy consumed for energy accumulated in the energy storage from fuel energy inputted to the system, and power energy outputted from the system to an operational element; when electrical energy accumulated in the energy storage is being discharged, it determines the energy efficiency of the entire system from fuel energy inputted to the system and the calculated energy efficiency related to the energy storage. A system efficiency improving device controls a control element related to a control-related parameter so that the instantaneous efficiency of the system is maximized. (Refer to JP-A-2005-198360, for example.)
Since the energy transfer system of a vehicle is constructed of machines and mechanisms, it is impossible to completely prevent an energy transfer function from becoming abnormal. When an energy transfer function is abnormal, energy transfer is not carried out as intended, and in general, output energy is reduced and the intended functions of the energy transfer system are not fulfilled.
Therefore, the following operation is effective for the user of a vehicle to maintain the functions of the vehicle: it is detected that the energy transfer function is abnormal, and a warning is sent out and the user is prompted to carry out repair or maintenance work.
However, conventionally known techniques in relation to energy transfer cannot diagnose any anomaly in an energy transfer system.
The invention has been made to solve the above problem, and it is an object of the invention to provide a diagnosis device for energy transfer in a vehicle that detects any anomaly in an energy transfer function and sends out a warning or prompts repair or maintenance work and thus is useful in taking appropriate action.